As shown in FIG. 11, an EL element emits light in color corresponding to the fluorescent substance by coupling a hole and an electron, injected from facing electrodes 2, 7, in an organic light emitting layer 5, and exciting a fluorescent substance in the organic light emitting layer 5 by this energy, and it attracts the attention as a white light sheet-form display element.
In particular, since an organic thin film EL display using an organic light emitting material has high light emitting efficiency such that it realizes a high brightness light emission with less than 10 V applied voltage, and capable of emitting light with a simple element structure. Therefore, application thereof to the advertisement which displays a specific pattern by light emission or other inexpensive simple displays is expected.
In the manufacturing of the display using the EL element, in general, an electrode layer and an organic light emitting layer are patterned. As the method for patterning the EL element, there are, a method of depositing the light emitting material on an electrode substrate via a shadow mask, a method of divisional coating of the organic light emitting material by the ink jet method in a pattern, a method of destroying a specific organic light emitting layer by the ultraviolet ray irradiation, a method of pattern printing of an organic light emitting material by the screen printing method, etc. However, in these methods, it is impossible to realize all of, the high light emitting efficiency and light taking out efficiency, the manufacturing process simplicity, and the highly sophisticated pattern formation.
As a means for solving the above mentioned problems, a method for manufacturing an EL element by patterning the organic light emitting layer using a photolithography method has been proposed. According to the method, compared with the conventionally executed patterning method by the deposition, since vacuum equipment comprising a highly accurate alignment mechanism or the like is not needed, the EL element can be manufactured relatively easily and inexpensively.
In contrast, compared with the patterning method using the ink jet method, the photolithography method is preferable in that a pre-process to a structure for helping patterning or a base member is not executed. Furthermore, in accordance with the ejection accuracy of an ink jet method, the photolithography method can be considered as a method more preferable for the highly sophisticated pattern formation.
However, in the photolithography method, a developing agent and a rinsing agent are needed to be used at the time of patterning the resist. Furthermore, since the above mentioned processes are needed to be repeated for three times to enable the full color display of the EL element, penetration of the developing agent or the rinsing agent to the organic light emitting layer brings about deterioration of the element characteristics. Therefore, a method for manufacturing an EL element without the need of the developing agent and the rinsing agent is called for.